FML or how I made myself unhireable

TL;DR: Working as a QA.
Changed jobs.
New job sucked.
Left after three months.
Got laid off from the next one after 4 months (not my fault).
Got depressed.
Got a Dev job back in the first company.
Job sucks, cannot leave… (5 months in)

Full rant:
I was doing pretty well as a QA Enginner. Started with internship, then junior in company A, then big pay rise moving to company B, where I quickly got promoted to Senior. As I was nearing 3yrs of exp, I decided it’s time for a change, as things were getting worse project-wise and felt like I was regressing. Also I was constantly bombarded with offers of +50% of my salary I could easily land, while company offered 10%.

Moved on to company C. This is where it started getting rocky. I was told I would be working on this one project, strictly test automation, nothing exciting but an easy gig. However week in, I was told to work on this other project 50/50. This was a startup kind of thing. It was a nightmare. Only manual testing. Most tickets had only a vague title, no description, no requirements, nothing. How do one test something without any knowledge how it should work? Besides that, the project lead on the client side was aggressive sometimes.
The workload was immense - 4 devs, 2 of them doing heavy overtime, so the output was like 6 devs and half of a tester….
Despite raising the problems, nothing was going to change, nor I could switch projects. The job began to heavily affect my mental health. Decided not to prolong my contract and left after 3 month probation period.

Quickly landed a job in company D. As my burnout as a tester kept bothering me more and more I decided that this was going to be my last job as a QA and next one will be a Dev. You see, I never enjoyed the tester part, I always enjoyed the automation part more. The plan was to learn in free time and after 18-24 months start applying for a dev role to see if I can land one (switching inside D was not an option). All plans went to hell, as I was handed a one month notice by the end of my third month. A month before my wedding… I was told the company was having financial issues and was laid off with about 30% of people in the company (mostly new hires).

I got depressed. I wouldn’t get out of bed for a few days. I never thought something like this would ever happen to me. Standing by my decision I was applying for development jobs, but most recruiters seeing either only QA experience or my recent 3 and 4 month employment periods weren’t responsive. Applying for testing jobs was a bit better but still nothing like before C and D.

Since company B I stayed in touch with my former manager, and he kept telling me that a new team has taken over most of the shitty work, and they are now working on cooler stuff and have more coming. He encouraged me to come back, as he has always thought highly of me professionally.
Looking at my options, I could probably get another testing job with lower pay, maybe I could land a junior Dev with like 1/3 of my salary or I could go back. So in my dark time I have reached out to my manager and just like that he got me a Senior Dev position, same pay as in company D.

Finally what I wanted right? Yeah… As soon I as joined all the new initiatives were being dropped one by one, and backlog got flooded with bugs and sh*t again. Five months in I hate my job again. Cannot leave cause no one will hire me…

Where I made the mistake?
Shouldn’t leave B despite facing regression and being underpaid?
Shouldn’t leave C no matter what?
Shouldn’t come back to B?